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| author | luxufan <luxufan@iscas.ac.cn> | 2022-12-05 19:38:25 +0800 |
|---|---|---|
| committer | luxufan <luxufan@iscas.ac.cn> | 2022-12-05 19:54:13 +0800 |
| commit | b0f78769178ebb5e0691aca5143fead7f79ee55c (patch) | |
| tree | 05d73c16d621076102d42712603b420f14c8a61d /llvm/lib/CodeGen/CodeGen.cpp | |
| parent | fc85ccd7b3cf7e6a7e7aef9e04c181df15b543e3 (diff) | |
| download | llvm-b0f78769178ebb5e0691aca5143fead7f79ee55c.zip llvm-b0f78769178ebb5e0691aca5143fead7f79ee55c.tar.gz llvm-b0f78769178ebb5e0691aca5143fead7f79ee55c.tar.bz2 | |
[SCCP] Propagate equality of a not-constant
The equality state of a not-constant can be used to do constant
propagation. For example,
```
define i32 @equal_not_constant(ptr noundef %p, ptr noundef %q) {
entry:
%cmp = icmp ne ptr %p, null
br i1 %cmp, label %if.then, label %if.end
if.then: ; preds = %entry
%cmp.then = icmp eq ptr %p, %q
br i1 %cmp.then, label %if.then1, label %if.end
if.then1: ; preds = %if.then
%cmp.then1 = icmp ne ptr %q, null
call void @use(i1 %cmp.then1)
br label %if.end
if.end:
ret i32 0
}
```
In this case, we can fold `%cmp.then1` as `true`.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D139289
Diffstat (limited to 'llvm/lib/CodeGen/CodeGen.cpp')
0 files changed, 0 insertions, 0 deletions